The present invention relates to clip nut assemblies for use with thin sheets having pre-punched holes, and more particularly, to a clip nut assembly having a nut which is self-aligning over a broad range of sheet material thicknesses. The clip portion of the assembly is of a geometry which approaches constant strain so that the possibility of permanent strain or set of the clip portion is reduced.
Prior known clip nut devices include resilient clips of a generally U-shaped configuration. During installation of a U-shaped clip device on a piece of sheet material, one of the clamping portions will deflect and pivot about a single axis located at the bight portion of the U-shaped clip in order to spring load the clip for retaining the device on the sheet. Such U-shaped devices also generally include a threaded nut which is retained for movement with the pivotable clamping portion. For these reasons, such known clip nut devices possess several limitations and disadvantages which reduce their utility and adaptability.
In particular, such devices yield substantial lateral and angular deflection of the nut relative to the sheet when utilized with sheets having thicknesses beyond a certain limit. The design of these devices therefore results in misalignment of the nut relative to the hole in the sheet in such applications. In an attempt to alleviate this inherent problem, some of these devices have provided a nut which is loosely retained, along with means to allow the user to manually pivot the nut back into axial alignment with the hole in the sheet. However, such devices still require threaded bolt installations which are time consuming and tedious in certain ranges of sheet material thickness, and impossible beyond that range.
Such known clip nut devices possess the additional disadvantage of a geometry which results in a permanent set or deformation of portions of the clip if they are utilized with sheet material having a certain threshold thickness. Such a permanent set will reduce the effectiveness of these devices in particular applications, since the clip must remain resilient to exert an effective clamping force on the sheet material. For these reasons, a user of such clip nut devices must stock a substantial inventory of clip nuts of varying size and type in order to accommodate a variety of sheet material applications.
It is, therefore, desirable to provide a clip nut assembly which can be effectively utilized over a greater range of sheet material thicknesses than presently known clip nut devices to allow a user to reduce its inventory of clip nut devices. It is moreover desirable to provide such a clip nut assembly which is self-aligning over its useful range to facilitate installation of threaded bolts utilized therewith. It is additionally desirable to provide such a clip nut assembly which reduces the possibility of permanent yield or set of the clip material so that the device can retain its effectiveness over a broad range of material thicknesses.
The clip nut assembly of the present invention includes a one piece clip which also serves as a nut retaining member. The clip is formed from an elongated piece of spring steel into a generally D-shaped configuration. When placed in this configuration, the clip defines two generally planar clamping portions spaced from and extending substantially parallel to one another, and an arcuate biasing portion which interconnects one end of one clamping portion with the opposite end of the other clamping portion. The biasing portion operates to bias the two clamping portions toward one another to enable these portions to clampingly engage a piece of sheet material inserted therebetween. Each clamping portion is provided with an aperture or hole, each of which is alignable with a pre-punched hole in the sheet material. One of the clamping portions has a threaded nut assembled and fixed for movement therewith. The nut includes a threaded bore which is coaxial with the apertures in the clamping portions.
The configuration of the clip nut assembly enables the clamping portion upon which the nut is assembled to pivot about a first axis defined by the interconnection between the biasing portion and the other clamping portion for positive angular deflection thereof relative to the other clamping portion to accommodate the thickness of a piece of sheet material during initial insertion thereof between the clamping portions. However, as the sheet material is further inserted between the clamping portions, the clamping portion-nut assembly pivots about a second axis defined by the interconnection between the biasing portion and this clamping portion to effect a negative angular deflection of these pieces relative to the other clamping portion. Complete insertion of the sheet material moves these pieces into proper alignment for installation of a threaded bolt. Such a design results in a clip nut configuration having an automatically self-aligning nut, and therefore avoids the disadvantages of nut misalignment associated with previously known devices.
The arcuate biasing portion of the device is provided with a generally diamond shaped aperture intermediate of its ends. This configuration achieves a resilient biasing member having constant strain characteristics. It therefore provides a clip nut assembly which distributes strain more evenly through the biasing portion, so that the assembly can accommodate a broader range of sheet material thicknesses without reaching the permanent yield point of the clip material. As is readily apparent, these features result in a clip nut assembly which can be effectively utilized over a broader range of material thicknesses than previously known devices, and therefore provides a device which allows a user to reduce its inventory of various types and sizes of clip nut devices.
The above and other features of the invention will become apparent from a reading of the detailed description of the preferred embodiments which makes reference to the following set of drawings.